The Causes of Low Platelet Counts

Updated April 17, 2017

Platelets,which are blood cell fragments, circulate within the bloodstream and trigger the formation of blood clots after an injury to a blood vessel to prevent excessive bleeding. A normal platelet count varies from 150,000 to 450,000 platelets per microliter of blood. Thrombocytopenia, the medical term for low platelets, results from a number of internal and external issues. If left untreated, thrombocytopenia can morph into a serious condition that can cause haemorrhages, internal bleeding and even death.

Decreased Platelet Production

Bone marrow produces large cells called megakaryocytes, which eventually breakdown into platelets. A condition or disease that adversely affects the health of the bone marrow results in decreased megakarocyte production and subsequent platelet formation. Diseases that harm the bone marrow include leukaemia, lymphoma, serious viral infections such as HIV, certain types of anaemia and cirrhosis, according to the Mayo Clinic.


The spleen is an organ that is part of the immune system. It normally helps fight infections by filtering harmful materials from the blood. However, when the spleen abnormally increases in size, it harbours a large amount of blood, which decreases the number of platelets in circulation. Hyperspleenism can result from cirrhosis, lymphoma, inflammatory diseases and tuberculosis.

Increased Platelet Breakdown

Certain secondary conditions can cause your body to use up platelets faster than the bone marrow can produce them. This leads to fewer platelets circulating in the blood. These conditions include pregnancy, which causes only mild thrombocytopenia, autoimmune diseases, such as lupus, bacterial infections in the blood and thrombotic thrombocytopenic purpura, a rare disease that causes random blood clots to form throughout the body.


Medications that suppress the immune system can also lead to decreased platelets. These include chemotherapy drugs and proton-pump inhibitors that work against gastric reflux disease. Other frequently used medications that cause thrombocytopenia are heparin, quinidine, anticonvulsants and certain antibiotics.


The symptoms for a low platelet count relate directly to abnormal or excessive bleeding. You should consult your medical provider if you notice prolonged bleeding from cuts and other injuries, unusually heavy menstrual flows, excessive bruising, spontaneous nose or gum bleeding or blood in the urine or stool.

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About the Author

Ann Jamerson began writing ads and informational brochures for research trials in 2003 during an internship at an alcohol and drug research center. She assisted in writing and editing manuscripts concerning the breast cancer genes and psychosocial effects on affected patients. She received her Bachelor of Science in biology from the University of California, San Diego and is currently attending nursing school.